The aim of this research is two fold: to elucidate new patterns of structure in nucleic acids and to determine the geometry of protein-nucleic acid recognition. The principle technique employed will be X-ray crystallography. In order to study nucleic acid structure, we shall determine the crystal structures of oligonucleotides, rare or modified bases and metal phosphodiester complexes. Nucleic acids and proteins coexist in chromosomes, ribosomes and viruses and must necessarily recognize one another during the processes of replication, transcription and translation. We shall study two classes of model compounds in order to define the geometry of nucleic acid-protein interaction: complexes and covalently linked components of nucleic acids and proteins. The latter compounds are of intrinsic biological interest because some are antibiotics, some are product inhibitors of biological methylation and some are radiation products. Hence we may be able to better define the mechanism of the processes in which they are involved. Finally, we shall initiate studies on a proteins which is known to relax supercoiled DNA and which may be critical to the processes of replication.